Abstract:

Methods for forming foamed polyurethane composite materials in an extruder
including a vacuum section are described. One method includes introducing
a polyol, a di- or poly-isocyanate, and an inorganic filler to a first
section of an extruder and mixing the components. After mixing, the
composite material is advanced to a second section of the extruder, which
is maintained at a vacuum pressure. The composite material can begin
foaming in the second section and then be extruded from the output end of
the extruder. The vacuum pressure of the second section removes
non-foaming related gasses entrained in the composite material. A further
method includes directing the extruded composite material into a mold.

Claims:

1. A method of forming a foamed polyurethane composite material in an
extruder, the method comprising:introducing a polyol, a di- or
poly-isocyanate, and an inorganic filler to a first section of an
extruder;mixing the polyol, the di- or poly-isocyanate, and the inorganic
filler in the first section to produce a composite material;advancing the
composite material to a second section of the extruder, the second
section being maintained at a vacuum pressure;foaming the composite
material in the second section;extruding the composite mixture from an
output end of the extruder,wherein the vacuum pressure in the second
section removes non-foaming related gasses entrained in the composite
material.

2. The method of claim 1, wherein the vacuum pressure is maintained using
a vacuum source.

3. The method of claim 1, wherein the vacuum pressure is maintained at 1
to 25 inHg.

4. The method of claim 1, wherein the inorganic filler is fly ash.

5. The method of claim 1, further comprising adding fiber in the first
section of the extruder.

6. The method of claim 1, further comprising introducing a foaming agent.

7. The method of claim 6, wherein the foaming agent is water.

8. The method of claim 7, wherein the foaming agent initiates a foaming
reaction prior to extruding the composite mixture.

9. The method of claim 1, wherein the composite mixture continues to foam
after the composite mixture is extruded.

10. The method of claim 1, further comprising cooling the second section
to control the rate of foaming.

11. A method of forming a molded article using a foamed polyurethane
composition comprising:introducing a polyol, a di- or poly-isocyanate,
and an inorganic filler to a first section of an extruder;mixing the
polyol, the di- or poly-isocyanate, and the inorganic filler in the first
section to produce a composite material;advancing the composite material
to a second section of the extruder, the second section being maintained
at a vacuum pressure;foaming the composite material in the second
section;extruding the composite mixture from an output end of the
extruder into a mold,wherein the vacuum pressure removes non-foaming
related gasses entrained in the composite material.

12. The method of claim 11, wherein the mold is a continuous mold.

13. The method of claim 11, wherein the vacuum pressure is maintained
using a vacuum source.

14. The method of claim 11, wherein the vacuum pressure is maintained at 1
to 25 inHg.

15. The method of claim 11, wherein the inorganic filler is fly ash.

16. The method of claim 11, further comprising adding fiber in the first
section of the extruder.

17. The method of claim 11, further comprising introducing a foaming
agent.

18. The method of claim 17, wherein the foaming agent is water.

19. The method of claim 11, wherein the composite mixture continues to
foam when the composite mixture enters the mold.

20. The method of claim 11, further comprising cooling the second section
to control the rate of foaming.

[0002]During composite mixing or polymer formation in an extruder, various
gasses present in the extruder can become mixed into the polymer created
and form entrained gaseous pockets. These pockets of gasses can create
areas of weakness or non-uniform density in a product made from the
polymer formulated in the extruder. Foamed products created in an
extruder can include these entrained gaseous pockets in addition to their
desired foam pockets. The ability to remove entrained gaseous pockets
from composites including foamed composites would be helpful in creating
products with uniform properties.

SUMMARY

[0003]Methods for forming a foamed polyurethane composite material in an
extruder are described. A first method of forming a foamed polyurethane
composite material in an extruder includes the step of introducing a
polyol, a di- or poly-isocyanate, and an inorganic filler to a first
section of an extruder. After introduction, the polyol, the di- or
poly-isocyanate, and the inorganic filler are mixed in the first section
to produce a composite material. Next the composite material is advanced
to a second section of the extruder that is maintained at a vacuum
pressure. The composite material can begin foaming in the second section
of the extruder. Finally, the composite mixture is extruded from an
output end of the extruder. The vacuum pressure in the second section
removes non-foaming related gasses entrained in the composite material.

[0004]A further method involves forming a molded article using a foamed
polyurethane composition. The method includes the step of introducing a
polyol, a di- or poly-isocyanate, and an inorganic filler to a first
section of an extruder. After introduction, the polyol, the di- or
poly-isocyanate, and the inorganic filler are mixed in the first section
to produce a composite material. Next the composite material is advanced
to a second section of the extruder that is maintained at a vacuum
pressure. The composite material is foamed in the second section of the
extruder. Finally, the composite mixture is extruded from an output end
of the extruder. The vacuum pressure in the second section removes
non-foaming related gasses entrained in the composite material.

[0005]The details of one or more embodiments of the invention are set
forth in the accompanying drawings and the description below. Other
features, objects, and advantages of the invention will be apparent from
the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

[0006]FIG. 1 is a schematic of an extruder system with a section
maintained at a vacuum pressure.

[0007]FIG. 2 is a schematic of an molding system including an extruder
system with a section maintained at a vacuum pressure and a mold into
which extruded material is directed.

[0008]FIG. 3 is a schematic of a control system for use of the vacuum in
the extruder system.

[0009]Like reference symbols in the various drawings indicate like
elements.

DETAILED DESCRIPTION

[0010]Methods for forming foamed polyurethane composite materials in an
extruder are described herein. One method includes introducing a polyol,
a di- or poly-isocyanate, and an inorganic filler to a first section of
an extruder and mixing the components. After mixing, the composite
material is advanced to a second section of the extruder, which is
maintained at a vacuum pressure. The composite material can begin foaming
in the second section then extruded from the output end of the extruder.
The vacuum pressure of the second section removes non-foaming related
gasses entrained in the composite material. A further method includes
introducing a polyol, a di- or poly-isocyanate, and an inorganic filler
to a first section of an extruder and mixing the components. After
mixing, the composite material is advanced to a second section of the
extruder, which is maintained at a vacuum pressure. The composite
material is foamed in the second section then extruded from the output
end of the extruder. The extruded composite can then be directed into a
mold. The vacuum pressure of the second section removes non-foaming
related gasses entrained in the composite material.

[0011]Components of an extruder system 10 useful in implementing the
methods described herein are shown in FIG. 1. Extruder system 10 includes
an extruder barrel 20 with an output end 30, a first section 40, a second
section 50, a first input 60, and a second input 70. Polyol, isocyanate,
and inorganic filler are introduced to the first extruder section 40
through the first input 60. Fiber and other materials can be introduced
to the first extruder section 40 through the second input 70 as desired.
The second section 50 is maintained at a vacuum pressure using a vacuum
source such that the vacuum pressure in the second extruder section
removes non-foaming related gasses entrained in the composite material.
As used herein, the phrase removes non-foaming related gasses is intended
to indicate that the method is intended to remove gasses that were
entrained in the composite material prior to the foaming reaction.
However, the removal of a limited amount of gasses present within the
composite material due to foaming is intended to be within the scope of
the appended claims.

[0012]A vacuum can be maintained in the second section 50, for example, by
the use of a conventional vacuum pump or vacuum generator. The use and
selection of vacuum pumps or vacuum generators for use with an extruder
is well known to those of skill in the art. An example of a useful vacuum
generator is model VDF 200 from Vaccon Vacuum Products (Vaccon Co., Inc.;
Medfield, Mass.). As used herein, the term vacuum is intended to mean a
pressure less than atmospheric pressure (i.e., 29.92 inches of mercury
(inHg)). Thus, a pressure of less than 29.92 inHg indicates a vacuum
pressure. Vacuum pressures of between 1 inHg and 25 inHg, 2 inHg and 20
inHg, 5 inHg and 15 inHg, and 8 inHg and 12 inHg are useful with the
methods described herein. Further, vacuum pressures of 25 inHg or less,
20 inHg or less, 15 inHg or less, 12 inHg or less, 10 inHg or less, or 5
inHg or less are also useful. A vacuum pressure of about 10 inHg is
particularly useful.

[0013]Components of a further extruder system 100 useful in implementing
the methods described herein are shown in FIG. 2. The extruder system 100
includes an extruder barrel 20 with an output end 30, a first section 40,
a second section 50, a first input 60, and a second input 70 each as
described above. The extruder system 100 further includes a mold 110 into
which the composite mixture extruded from the output end of the extruder
30 is directed. Polyol, isocyanate, and inorganic filler are introduced
to the first extruder section 40 through the first input 60. Fiber and
other materials can be introduced to the first extruder section 40
through the second input 70 as desired. The second section 50 is
maintained at a vacuum pressure using a vacuum source such that the
vacuum pressure in the second extruder section removes non-foaming
related gasses entrained in the composite material.

[0014]The types of molds useful with extruded polymer composite materials
are well known to those of skill in the art. Extruded polymer composite
materials are often extruded through a profile die that imparts a shape,
such as a tubular shape, to the extruded polymer composite material.
Additionally, an extruded polymer composite material can be directed into
a mold cavity to adopt the shape of the mold through compression or
expansion. With the use of molds external to an extruder, a user will
account for the continuous nature of the extruded composite material,
i.e., the material will continue to be extruded and material can be lost
if the transition time between the availability of mold cavities is not
accounted for. One useful molding technique for extruded composite
material is to use a continuous mold. One example of a continuous mold is
a continuous belt mold. A continuous belt mold is a cavity formed between
two or more belts that provide a shape for the extruded material to
adopt. The forming belts wrap around rollers or similar devices and
return to continuously form a mold cavity.

[0015]As shown in FIG. 3, a controller 200 can be used to control the
vacuum in the second section 50. The controller 200 is operatively
interconnected with a vacuum device 210, such as a vacuum pump. The
controller 200 has hardware and/or software configured for operation of
the vacuum device 210, and may comprise any suitable programmable logic
controller or other control device, or combination of control devices,
that is programmed or otherwise configured to perform the process
described herein. The controller 200 can control the vacuum device 210
based on an input signal 220. The input signal 210 can be a desired
pressure for the second section 50. Additionally, the controller 200 can
control or provide instructions to one or more devices controlling the
addition of materials 230 to the extruder. Further, the controller 200
can control or provide instructions to a mold control system 240.

[0016]Various foamed polyurethane composite materials may be created using
an extruder and the methods described herein. Extrusion allows for
thorough mixing of the various components of the composite material. The
extruder components may be configured in various ways to provide a
substantially homogeneous mixture of the various components of the
composite material. The various components of a foamed polyurethane
composite material (e.g., polyol, di- or poly-isocyanate, and inorganic
filler) may be added in different orders and at different positions in an
extruder through various input devices (e.g., hoppers, feed chutes, or
side feeders). As used herein, the term composite material is intended to
include the components of a polymeric material made in situ in an
extruder. Hence, a method step referring to introducing component
materials to an extruder includes the addition of components that will
react to form a polymeric material in situ in an extruder. Such reactions
may be controlled by various additives and reaction conditions. For
example, surfactants may be used to control cell structure and catalysts
may be used to control reaction rates. An example of a polyurethane
composite material formed in situ may include one or more of a polyol, a
monomeric or oligomeric di- or poly-isocyanate, an inorganic filler, a
fibrous material, a catalyst, a surfactant, a colorant, a coupling agent,
and other various additives. The various materials added to an extruder
may be metered into the extruder through metering devices or other means.
Continuous feeding of the respective components of the polymeric
composite material results in a continuous process of extruding the
polymeric composite material. Extruder technology is well known to those
of skill in the art.

[0017]Fillers as used with the methods described herein include
particulate material. With the addition of such fillers, the composite
materials may still retain good chemical and mechanical properties. These
properties of the composite material allow for its use in building
materials and other structural applications. Advantageously, the
composite material may contain large loadings of filler content without
substantially sacrificing the intrinsic structural, physical, and
mechanical properties of the polymer. Examples of fillers useful with the
compositions described herein include, but are not limited to, fly ash
and bottom ash; wollastonite; ground waste glass; granite dust; calcium
carbonate; perlite; barium sulfate; slate dust; gypsum; talc; mica;
montmorillonite minerals; chalk; diatomaceous earth; sand; bauxite;
limestone; sandstone; microspheres; porous ceramic spheres; gypsum
dihydrate; calcium aluminate; magnesium carbonate; ceramic materials;
pozzolanic materials; zirconium compounds; vermiculite; pumice; zeolites;
clay fillers; silicon oxide; calcium terephthalate; aluminum oxide;
titanium dioxide; iron oxides; calcium phosphate; sodium carbonate;
magnesium sulfate; aluminum sulfate; magnesium carbonate; barium
carbonate; calcium oxide; magnesium oxide; aluminum hydroxide; calcium
sulfate; barium sulfate; lithium fluoride; calcium hydroxide; and other
solid waste materials. Other acceptable fillers will be known to those of
skill in the art. Fly ash is useful because it is uniform in consistency
and contains carbon, which can provide some desirable weathering
properties to the product due to the inclusion of fine carbon particles
which are known to provide weathering protection to plastics, and the
effect of opaque ash particles which block UV light. Ground glass (such
as window or bottle glass) is also useful as it absorbs less resin,
decreasing the cost of the composite.

[0018]Particulate materials with a broad particle size distribution having
multiple modes can advantageously be used with the composites described
herein. Examples of such particulate materials can be found in U.S. Pat.
Nos. 6,916,863 and 7,241,818, which are incorporated herein by reference
in their entirety. Specifically, a fly ash filler or filler blend having
a particle size distribution with at least three modes can be used.
Preferably, the particle size distribution includes a first mode having a
median particle diameter from 0.3 to 1.0 microns, a second mode having a
median particle diameter from 10 to 25 microns, and a third mode having a
median particle diameter from 40 to 80 microns. The particle size
distribution also preferably includes 11-17% of the particles by volume
in the first mode, 56-74% of the particles by volume in the second mode,
and 12-31% of the particles by volume in the third mode. Moreover, the
ratio of the volume of particles in the second and third modes to the
volume of particles in the first mode is preferably from about 4.5 to
about 7.5. A filler comprising a fly ash having a particle size
distribution having at least three modes can further include one or more
additional fillers other than the fly ash.

[0019]The composite materials described herein additionally comprise
blends of various fillers. For example, coal fly ash and bottom ash can
be used together as a mixture. Composite materials utilizing filler
blends may exhibit better mechanical properties such as impact strength,
flexural modulus, and flexural strength. A further advantage in using
filler blends is compatibility in particle size distribution that can
result in higher packing ability in certain blends.

[0020]The composite materials described herein can comprise about 20 to
about 95 weight percent of inorganic filler, which includes, for example,
approximately 20, 25, 30, 35, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60,
62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, or 94
weight percent of filler. These amounts are based on the total amount of
filler used, and only one type of filler (e.g., fly ash), or filler
blends (e.g. fly ash and dust) can be used. In certain embodiments, the
polymeric composite material may contain the filler in an amount within a
range formed by two of the foregoing approximate weight percents.
Additionally, the composite materials can comprise about 30 to about 90
weight percent of inorganic filler, about 40 to about 87.5 weight percent
of inorganic filler, about 50 to about 85 weight percent of inorganic
filler, about 60 to about 82.5 weight percent, or about 65 to about 80
weight percent of inorganic filler. As used herein, weight percent refers
to the relative weight of the filler component compared to the total
weight of the composite material.

[0021]Fibers can also be added (e.g., in the first section 40 of the
extruder such that the composite materials possess good chemical and
mechanical properties as described regarding the use of fillers).
Exemplary fibers can include reinforcing fibers and can include fibers
such as chopped fiberglass (chopped before or during mixing in an
extruder), rovings, basalt, PVA fibers, carbon fibers, linear tows,
wollastonite, or fabrics. The reinforcing fibers can range in length, for
example, from about 0.1 in. to about 2.5 in, from about 0.2 in to about 2
in., from about 0.25 in. to about 1 in., or from about 0.25 in. to about
0.5 in. Such fibers can, for example, be fed from a spindle or otherwise
provided as known to those of skill in the art.

[0022]The reinforcing fibers give the material added strength (flexural,
tensile, and compressive), increase its stiffness, and provide increased
toughness (impact strength or resistance to brittle fracture). The use of
rovings or tows increases flexural stiffness and creep resistance.
Specifically, the dispersed reinforcing fibers may be bonded to the
polymeric matrix phase, thereby increasing the strength and stiffness of
the resulting material. This enables the material to be used as a
structural synthetic lumber, even at relatively low densities (e.g.,
about 20 to about 60 lb/ft3).

[0023]Composite materials as described herein may be formed with a desired
density to provide structural stability and strength. In addition, the
composite material can be easily tuned to modify its properties by, e.g.,
adding oriented fibers to increase flexural stiffness, or by adding
pigment or dyes to hide the effects of scratches. Also, such composite
materials may also form a "skin," i.e., a tough, slightly porous layer
that covers and protects the more porous material beneath. Such skin can
be tough, continuous, and highly adherent, and can provide excellent
water and scratch resistance.

[0024]As discussed above, one of the monomeric components used to form a
foamed polyurethane composite material is a poly- or di-isocyanate (an
aromatic diisocyanate or polyisocyanate may be used). The poly- or
di-isocyanate can be monomeric or polymeric. In certain embodiments
methylene diphenyl diisocyanate (MDI) is used. The MDI can be MDI
monomer, MDI oligomer, or mixtures thereof. The particular MDI used can
be selected based on the desired overall properties, such as the amount
of foaming, strength of bonding to the inorganic particulates, wetting of
the inorganic particulates in the reaction mixture, strength of the
resulting composite material, and stiffness (elastic modulus).

[0025]Suitable MDI compositions include those having viscosities ranging
from about 25 to about 200 cp at 25° C. and NCO contents ranging
from about 30% to about 35%. Generally, isocyanates are used that provide
at least 1 equivalent NCO group to 1 equivalent OH group from the
polyols, preferably with about 5% to about 10% excess NCO groups.
Suitable examples of aromatic polyisocyanates include 4,4-diphenylmethane
diisocyanate (methylene diphenyl diisocyanate), 2,4- or 2,6-toluene
diisocyanate (including mixtures thereof), p-phenylene diisocyanate,
tetramethylene and hexamethylene diisocyanates, 4,4-dicyclohexylmethane
diisocyanate, isophorone diisocyanate, and mixtures of 4,4-phenylmethane
diisocyanate and polymethylene polyphenylisocyanate. In addition,
triisocyanates such as, 4,4,4-triphenylmethane triisocyanate;
1,2,4-benzene triisocyanate; polymethylene polyphenyl polyisocyanate; and
methylene polyphenyl polyisocyanate, may be used. Isocyanates are
commercially available from Bayer Corporation (Pittsburgh, Pa.) under the
trademarks MONDUR and DESMODUR. Isocyanates suitable for use with the
composites described herein include Bayer MRS-4, Bayer MR Light, Dow PAPI
27 (Dow Chemical Company; Midland, Mich.), Bayer MR5, Bayer MRS-2, and
Huntsman Rubinate 9415 (Huntsman Polyurethanes; Geismar, La.).

[0026]As indicated above, the isocyanate is reacted with one or more
polyols. In general, the ratio of isocyanate to polyol (isocyanate
index), based on equivalent weights (OH groups for polyols and NCO groups
for isocyanates) is generally in the range of about 0.5:1 to about 1.5:1.
Additionally, the isocyanate index can be from about 0.8:1 to about
1.1:1, from about 0.8:1 to about 1.2:1, or from about 1.05:1 to about
1.1:1. Ratios in these ranges provide good foaming and bonding to
inorganic particulates, and yields low water pickup, fiber bonding, heat
distortion resistance, and creep resistance properties. A particularly
useful isocyanate index is from 1.05:1 to 1.1:1.

[0027]Polyols useful with the methods described herein may be single
monomers, oligomers, or blends. Mixtures of polyols can be used to
influence or control the properties of the resulting composite material.
The properties, amounts, and number of polyols used may be varied to
produce a desired polyurethane composite material. Useful polyols include
polyester and polyether polyols. Polyether polyols are commercially
available from, for example, Bayer Corporation (Pittsburgh, Pa.) under
the trademark MULTRANOL. Polyols useful with the methods described herein
include polyether polyols, such as MULTRANOL, including MULTRANOL 3400
and MULTRANOL 4035, ethylene glycol, polypropylene glycol, polyethylene
glycol, diethylene glycol, triethylene glycol, dipropylene glycol,
glycerol, 2-pentane diol, pentaerythritol adducts, 1-trimethylolpropane
adducts, trimethylolethane adducts, ethylenediamine adducts,
diethylenetriamine adducts, 2-butyl-1,4-diol, neopentyl glycol,
1,2-propanediol, pentaerythritol, mannitol, 1,6-hexanediol, 1,3-buytylene
glycol, hydrogenated bisphenol A, polytetramethyleneglycolethers,
polythioethers, and other di- and multi-functional polyethers and
polyester polyethers, and mixtures thereof. Additionally, plant-based
polyols (such as castor, canola, and soy oil polyols), polycarbonate
polyols, phenolic polyols, and acrylic polyols can be used. Examples of
plant based polyols useful with the methods described herein include
ECOPOL 122, ECOPOL 123, ECOPOL 124, ECOPOL 131, and ECOPOL 132, which are
aromatic polyester polyols based on soybean oil grafted with polyethylene
terephthalate (PET) from ECOPUR Industries Inc. (Dallas, Tex.).

[0028]Additional components useful with polyurethanes include
chain-extenders, cross-linkers, blowing agents, UV stabilizers,
anti-oxidants, pigments, coupling agents, surfactants, and catalysts.
Though the use of such components is well known to one of skill in the
art, some of these additional additives are further described herein.

[0029]Low molecular weight reactants such as chain-extenders and/or
cross-linkers can be included in the polyurethane composite materials
described herein. These reactants help the polyurethane system to
distribute and contain the inorganic filler and/or fibers within the
polyurethane composite material. Chain-extenders are difunctional
molecules, such as polyols or amines, that can polymerize to lengthen the
urethane polymer chains. Examples of chain-extenders include the
1,4-butane diol; 4,4'-Methylenebis (2-Chloroaniline) (MBOCA); and
diethyltoluene diamine (DETDA). Cross-linkers are tri- or greater
functional molecules that can integrate into a polymer chain through two
functionalities and provide one or more further functionalities (i.e.,
linkage sites) to cross-link to additional polymer chains. Examples of
cross-linkers include ethylene glycol, glycerin, trimethylolpropane, and
sorbitol. In some polyurethane composites, a cross-linker or
chain-extender may be used to replace a portion of the polyol.

[0030]Foaming agents (also known as blowing agents) may also be added to
the extruder (e.g., to the second section 40) to cause foaming. Examples
of blowing agents include organic blowing agents, such as halogenated
hydrocarbons, hexanes, and other materials that vaporize when heated by
the polyol-isocyanate reaction (such as water, which reacts with
isocyanate to yield carbon dioxide). The foaming agent can be added such
that the foaming agent initiates a foaming reaction prior to extruding
the composite mixture.

[0031]Among other parameters, the rate of foaming can be controlled by the
temperature of the composite materials when the foaming agent is added or
present. For example, increasing the temperature of the composite
material when a foaming agent is present increases the foaming reaction.
Similarly, cooling the composite material upon addition of foaming agent
can reduce the amount of foaming. Cooling the composite material to
reduce the amount of foaming is useful when a foaming reaction is desired
to be initiated in the extruder and continue once the composite material
is extruded from the output end of the extruder. For example, when an
extruded composite material is fed into a mold, if the foaming reaction
continues, the composite material can expand to fill the mold.

[0032]Ultraviolet light stabilizers, such as UV absorbers, can be added to
the polyurethane composite material. Examples of UV light stabilizers
include hindered amine type stabilizers and opaque pigments like carbon
black powder. Antioxidants, such as phenolic antioxidants can also be
added. Antioxidants provide increased UV protection, as well as thermal
oxidation protection.

[0033]Pigments or dyes optionally can be added to the polyurethane
composite material. An example of a pigment is iron oxide, which can be
added in amounts ranging from about 2 wt % to about 7 wt %, based on the
total weight of the composite material.

[0034]Catalysts are generally added to control the curing time of the
polymer matrix. Examples of useful catalysts include amine-containing
catalysts (such as DABCO and tetramethylbutanediamine) and tin-,
mercury-, and bismuth-containing catalysts. Multiple catalysts can be
used to increase uniformity and rapidity of cure. For example, a mixture
of 1 part tin-containing catalyst to 10 parts amine-containing catalyst
can be added to a reaction mixture in an amount up to about 0.10 wt %
(based on the total reaction mixture).

[0035]Surfactants may optionally be used as wetting agents and to assist
in mixing and dispersing the inorganic particulate material in a
composite. Surfactants also stabilize and control the size of bubbles
formed during foaming (if foaming is used) and passivates the surface of
the inorganic particulates, so that the polymeric matrix covers and bonds
to a higher surface area. Surfactants can be used in amounts below about
0.5 wt % based on the total weight of the mixture. Examples of
surfactants useful with the polyurethanes described herein include
silicone surfactants such as DC-197 and DC-193 (Air Products; Allentown,
Pa.), and other nonpolar and polar (anionic and cationic) products.

[0036]Coupling agents and other surface treatments such as viscosity
reducers or flow control agents can be added directly to the filler or
fiber (pre-treatment), or incorporated prior to, during, and/or after the
mixing and reaction of the polyurethane composite material. Coupling
agents allow higher filler loadings of an inorganic filler such as fly
ash and may be used in small quantities. For example, the polyurethane
composite material may comprise about 0.01 wt % to about 0.5 wt % of a
coupling agent. Examples of coupling agents useful with the polyurethanes
described herein include Ken-React LICA 38 and KEN-React KR 55 (Kenrich
Petrochemicals; Bayonne, N.J.).

[0037]Variations in the ratio of the polyol to the isocyanate in a
reactive mixture may result in variations in the polyurethane composite
especially with high inorganic filler loads. Additionally, changes in the
polyol to isocyanate ratio may result in changes to the process for
making the polyurethane composites. High filler loading in such systems
typically inhibits (i.e., physically blocks) the reaction or action of
the various polyurethane composite components, including the polyol, the
isocyanate, the surfactants, the coupling agents, and the catalysts.
Increasing the temperature during processing sometimes helps the
reactivity of the reactive mixtures. The use of excess isocyanate, i.e.,
an isocyanate index above 100, can give higher temperature exotherms
during the process of making the polyurethane composite material, which
can result in more cross-linking of the polyol and isocyanate, and/or a
more complete reaction of the hydroxyl groups and isocyanate groups.

[0038]An example of useful compositional ranges (in percent based on the
total composite composition) are provided below:

TABLE-US-00001
Component wt % range
Polyol about 2.5 to about 35
Isocyanate about 12 to about 15
Catalyst up to about 0.3
Surfactant up to about 0.5
Coupling Agent about 0.01 to about 0.5
Blowing Agent up to about 0.15
Pigment up to about 7
Fiber up to about 10
Filler about 20 to about 95

[0039]Additional components as described herein can be added in various
amounts that can be determined by persons having ordinary skill in the
art.

[0040]The present invention is not limited in scope by the embodiments
disclosed herein which are intended as illustrations of a few aspects of
the invention and any embodiments which are functionally equivalent are
within the scope of this invention. Various modifications of the
apparatus and methods in addition to those shown and described herein
will become apparent to those skilled in the art and are intended to fall
within the scope of the appended claims. Further, while only certain
representative combinations of the apparatus and method steps disclosed
herein are specifically discussed in the embodiments above, other
combinations of the apparatus components and method steps will become
apparent to those skilled in the art and also are intended to fall within
the scope of the appended claims. Thus a combination of components or
steps may be explicitly mentioned herein; however, other combinations of
components and steps are included, even though not explicitly stated. The
term "comprising" and variations thereof as used herein is used
synonymously with the term "including" and variations thereof and are
open, non-limiting terms. Although the terms "comprising" and "including"
have been used herein to describe various embodiments, the terms
"consisting essentially of" and "consisting of" can be used in place of
"comprising" and "including" to provide for more specific embodiments of
the invention and are also disclosed.